Automated two-speed peristaltic pump controller for reduced sample wash-out time and analysis of small sample volumes

Abstract

An easily assembled electronic controller is shown, which allows automatic selection of the ‘high-speed purge’ or ‘rabbit’ mode of the commonly used Gilson Minipuls 2 peristaltic pump. Application is demonstrated on an inductively coupled plasma mass spectrometer system consisting of a Perkin-Elmer SCIEX Model 250 with Model 5000 computer hardware and software, and a Gilson Model 212B autosampler. The controller places the peristaltic pump in the ‘high-speed purge’ mode when the sipper is at the autosampler wash station and maintains the ‘high-speed purge’ for an adjustable delay time after the sipper is moved from the wash station to a sample position. The time required for the wash solution to replace the sample solution in the transfer tubing and to flush the spray chamber can be typically reduced by more than 1 min. The pump controller also allows automated data acquisition using reduced liquid sample uptake rates (0.1 g min^–1), which allows analysis of <3 g of sample solution.